<!DOCTYPE html>
<html>
  <head>
    <style> * { color: red } </style>
    <style id="t"></style>
  </head>
  <body>
    <span class="test">This text should be green</span>
    <script>
      document.getElementById("t").
        appendChild(document.createTextNode("* { color: green }"));
    </script>
  </body>
</html>
